In one corner is a roster of climate change deniers who now run key congressional committees and the Environmental Protection Agency. In the other corner is Bill Nye the Science Guy, arguably the scientific community’s biggest advocate.

“I’ve got to fight this fight,” Nye says in the forthcoming documentary “Bill Nye: Science Guy,” as he hits back against a growing anti-science movement that questions evolution and humans’ contribution to climate change.

The film by David Alvarado and Jason Sussberg, which opens in Washington on Friday at the West End Cinema, shows Nye’s transition from PBS children’s show personality, a role that catapulted him to worldwide fame, to a pugilist taking on the likes of creationist crusader Ken Ham and climate change contrarian Joe Bastardi.

Nye throws himself into it on cable news, public debates and, following in the footsteps of his idol and onetime professor at Cornell, Carl Sagan, as chief executive officer of the Planetary Society.

He has his work cut out for him in today’s Washington.

EPA Administrator Scott Pruitt, for instance, has removed language about climate change from his agency’s website and has proposed barring scientists who have received EPA grants from serving on the agency’s scientific panels.

In April, Nye helped lead the March for Science in Washington, and he finds himself in the capital city frequently, particularly in his position as head of the Planetary Society.

“Space exploration is uniquely bipartisan. People from both sides of the aisle support space exploration almost all the time,” he said, pointing to the interest in NASA’s planned mission to Europa, one of Jupiter’s moons.

Whether he’ll also be pressing Congress and Washington to take action to stave off climate change is an open question, despite his recent advocacy on the topic.

“I hope I don’t have to frankly. I hope people figure it out sooner or later,” he said. He is optimistic that many members of Congress who reject climate science are constrained primarily by the politics of their districts, not their own beliefs.

“My understanding is there are a great many conservatives in both houses that are waiting for their opportunity to, as the saying goes, hold hands and come out in favor of climate change legislation and regulation,” he said.

Bill Nye signs an autograph before the start of a House Appropriations subcommittee hearing on science education in 2009. (CQ Roll Call file photo)

As for the immediate future, he is in Washington this week helping promote “Bill Nye: Science Guy.” Documenting his family history, testy moments and even episodes of doubt, the film presents a version of Nye that is more complex than his wacky TV personality.

“I pleaded with them to make me happier,” Nye said in jest of Alvarado and Sussberg. Nye, who had no creative input on the project, said, “I cringe a lot” when viewing some of the more sensitive moments in the movie, like when he is interviewed by a neuroscientist about the effect of fame on the brain, as well as his own issues with intimacy.

But the Bill Nye of the movie is a richer, more three-dimensional figure than the one many will remember from videos in their junior high science class.

As astrophysicist Neil deGrasse Tyson, a friend of Nye’s, says in the film, “Bill slowly but successfully transitioned from Bill Nye the Science Guy for kids to the Science Statesman.”

What’s more, the Washington, D.C., native is a Nationals fan, and was a Senators fan before.

“I’m absolutely, by no means, an Orioles fan,” he deadpanned — so perhaps expect to see him not just at the Capitol, but also down the street at Nationals Park.